It may depend on whether or not they carry a particular gene variation, Washington State University researchers discovered. Some people, the study found, are particularly vulnerable to the effects of sleep deprivation and are less likely to make good decisions based on changing information, says Hans Van Dongen, director of the WSU Sleep and Performance Research Center in Spokane.

"About one quarter of the participants in our study were particularly vulnerable to impairment in cognitive flexibility," Van Dongen says.

Others, he says, are able to fight the effects.

The study, published in late 2017, provides new insight into how people perform tasks when sleep deprived. And it has the attention of the United States Department of Defense, which recently funded WSU to launch a three-year project to study how to mitigate the effects of lack of sleep.

Van Dongen conducted the research with WSU psychology professors Paul Whitney, the lead author of the study, and John Hinson. Years ago, they discovered there are at least two separate elements of cognition affected by sleep deprivation. The first, which people have long known was an effect of sleep deprivation, is "vigilant attention," or the ability to focus on one thing while sleep deprived.

"It turns out that was only half the story," Van Dongen says.

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Hans Van Dongen

The second element of cognition affected by sleep deprivation is "cognitive flexibility," the ability to switch attention to something else if needed. In other words, it's the ability to adjust based on altered plans or expectations.

WSU researchers wanted to learn how lack of sleep impairs cognitive flexibility, and why. They selected 49 people to participate in the study. A majority of those participants were selected to go 38 hours without sleep. Research assistants kept the participants in the dimly lit WSU Sleep and Performance Research Lab and made sure nobody closed their eyes over that time.

The participants were shown a series of letter pairings on a computer then asked to click the left mouse for one letter combination and the right mouse for all others. Then, the researchers changed the game: They switched the letter patterns. That's the change that's supposed to test cognitive flexibility.

People who were well rested adapted to the changes quickly. None of the sleep-deprived participants were immune.

But perhaps a more surprising revelation is that the carriers of a specific gene variant, in what's called the DRD2 gene, were particularly impaired in this test, while carriers of a different gene variant were more resistant to the effects. (By the way, researchers say there's zero correlation with people who think they're resistant to sleep deprivation and those who actually are.)

This information has real-world impact. Take battlefield situations or disaster scenarios, Whitney says.

"There are lots of situations people find themselves in where circumstances are unfolding over time and you have to make a series of decisions," Whitney says.

There are more mundane impacts as well. Van Dongen says sleep deprivation can affect a person's ability to respond to new arguments in a conversation, or pivot to a new pitch when selling a product, for example.

He notes that there can be a trade-off for people who are more resistant to the effects of sleep deprivation. They may have more cognitive flexibility, but it can mean they're not as ready when an expectation is actually carried out.

So are there ways to minimize those genetic impacts? That's the question the military, and the WSU researchers, want to find out.

"It's a good question, but it's kind of wide open to what we can do to build resilience," Whitney says. "We just don't know right now."

The obvious answer is to find a way to take a nap. Coffee, exposure to bright light and social interaction can help you stay alert and helps with sustained attention. But none of those things will necessarily protect you from the effects of sleep deprivation, Whitney says. And in high-risk situations, they're not always possible.

The goal of the new study funded by the Department of Defense, which is supposed to launch this month, may demonstrate what it would look like to manipulate cognitive flexibility and make someone more resistant to going without sleep. Down the road, Van Dongen says the idea would be to potentially create a drug that only targets that portion of the brain.